1. Field of the Invention
This invention relates to improvements in automotive clutches and, in particular, to an improvement for mounting and supporting diaphragms in diaphragm clutches.
2. Brief Statement of the Prior Art
Diaphragm or Bellville clutches are the most commonly used in the automotive industry. In the typical automotive clutch, the clutch disc is supported between a pressure plate and the flywheel. A clutch housing cover which holds onto the flywheel surrounds the pressure plate and supports a spring diaphragm, also known as a Bellville diaphragm which supplies the clamp load to compress the clutch disc between the pressure plate and flywheel when the clutch is engaged. The diaphragm has a fulcrum support on the clutch housing cover and the base of the diaphragm rests on a raised circular rim on the upper surface of the pressure plate. When the diaphragm reverses its position between clutch engagement and disengagement, the base of the diaphragm rubs against this circular rim, with frictional losses that cause hysterisis in the clamp load between engagement and disengagement, and objectionable wear on the rim of the pressure plate.
The most common diaphragm clutches are the push off type in which a force is applied downwardly against the center fingers of the diaphragm to cause it to move release the pressure plate into a position disengaging the clutch disc. Recent changes, spurred by the desire to minimize size and bulk of automotive components has lead to the development of the pull off type clutch in which a lifting force is applied to the fingers of the diaphragm to release the pressure plate. In this clutch design, the base of the diaphragm rests against the underside of the clutch housing cover, and an inner annular area of the diaphragm bears against the raised rim on the pressure plate.
In both designs, however, the diaphragm rubs against a raised stationary rim of the upper surface of the pressure plate, and the clutches suffer the hysterisis and wear problems previously mentioned.
In my parent application, I have disclosed improvements in automotive clutches in which the diaphragm is supported by balls carried in a circular groove in the pressure plate and supported in circumferentially spaced-apart locations by a retainer ring. In the pull-off type of clutch, the base of the diaphragm is supported by balls carried on the undersurface of the clutch housing cover, and additional balls are provided on a raised rim on the pressure plate. While the invention as disclosed in my prior application secures a more efficient clutch operation than previous clutches, it is desirable to modify the invention to adapt it to mass manufacture and simplicity of installation.